That's a good article.
I read some similar, but less complete, info online as I was choosing a motor for our restoration. I wanted a higher performance motor to install and moth ball the 260. The Mexican block story was intriguing and a quick google search revealed one for sale not to far from home, so I picked it up. I probably overpaid for it at $500 delivered, but I do like the story. A friend has already volunteered to glue corona beer bottle caps to the front block "nubs".
The block was been built and dyno'd just after the last Presidential Election. I Go Pro'd the event and at one point the engine builder and dyno operator were having a chat while I was getting some ear protection. Later, when I watched the video, I got to hear a conversation between the two. The dyno guy was seemingly impressed with the mill and asked the builder about the details. The builder mentioned it was a Mexican block and the dyno guy interrupted him and said "That motor runs great, I sure hope Trump doesn't deport it". I still think it's hilarious.